AKULA 9000B USER MANUAL
/ SECTION 3
REV:EN05130513-03
Copyright 2006-2015 © Geoscanners AB
20
3.4.2
Gain Box
The electromagnetic waves suffer heavy attenuation as
it penetrates the materials and the reflections from the
objects in them are increasingly weaker with the increase
of the penetration depth. This is the reason why we need
to apply a non-linear gain function to the acquired data.
GAS™ allows up to six gain points to be selected to
define the gain curve that will be applied to the incoming
data. The amount of points is selected from the drop
down menu in the top of the gain box and the values for
each individual point are typed in in the corresponding
fields. These values are expressed in decibels and can
be selected within the maximum and minimum available
values for your particular ground penetrating radar
model.
It is important to notice that heavily over-gained signals
will never provided a good and useful data. Applying gain
to very long ranges will not make new data to appear,
but rather will distort the data that is available in the
more shallow regions. The effect in these cases will be
an increased amount of noise and a corruption of the
useful data. It is advisable to never allow the signals to
be clipping and a 75% full swing is a good figure of merit
when applying range gain.
To see the shape of the gain function you have entered
select the check box “Show Gain Line” and a line over
the oscilloscope view will show the gain profile you are
applying to the collected data.
Example of over-gained signal showing the transmitted or direct pulse clipping at the start.
